1. Technical Field
The present invention relates to a fluid injection device. More specifically, the present invention relates to a fluid injection device of simple construction that injects stable and strong pulses of fluid.
2. Related Art
Conventional fluid injection device as disclosed in the Japanese Unexamined Patent Application, First Publication No. 2005-152127, for example, is well known as a fluid injection device for dissecting or cutting out biopsy tissues.
This fluid injection device includes a micro-pump, a connection flow passage, and a connection tube.
The micro-pump changes the volume of the pump chamber and discharges the fluid.
The outlet flow passage of the micro-pump is connected to one end of the connection flow passage, and an opening (nozzle) made smaller than the diameter of the outlet flow passage is formed at another end of the connection flow passage.
The connection tube has a rigidity that is adequate to transmit the pulses of the fluid flowing from the micro-pump in which the connection flow passage to the opening is formed.
The fluid flows in this fluid injection device by repetitive pulse wave trains and pauses, and is injected at high speed from the opening.
In the Japanese Unexamined Patent Application, First Publication No. 2005-307743, the art of providing a piston pump and a pump priming device on the side of the outlet flow passage of the micro-pump configured as mentioned above, is disclosed.
According to this art, the priming operation is performed at start when fluid has not entered the micro-pump, and the air in the pump chamber is compressed and removed after the start of operation.
According to Japanese Unexamined Patent Application, First Publication No. 2005-152127, pulsating fluid can be injected at high speed and can be easily controlled.
While the ability to dissect tissues during surgery, for example, is high, the quantity of injection of pulsating fluid was low, and fluid rarely accumulated in the surgical field.
Consequently, visibility was enhanced and the scattering of tissues was effectively prevented.
This micro-pump required priming operation and elimination of air bubbles in the pump chamber at the start of operation based on the operating characteristics, and a construction with installation of the pump priming device as disclosed in the Japanese Unexamined Patent Application, First Publication No. 2005-307743, was proposed.
However, even if a pump priming device is installed, the priming device is disconnected and removed after start, and when air bubbles are generated in the pump chamber, the drive operation may become unstable.
Also, in the micro-pump according to the Japanese Unexamined Patent Applications, First Publication No. 2005-152127 and First Publication No. 2005-307743, the inertance on the outlet flow passage side is set greater than the inertance on the inlet flow passage side; thus, a check valve was installed on the inlet flow passage side to prevent back flow of the fluid.
This check valve is extremely small, and its washability is poor. Also, the check valve may not be able to maintain adequate performance for long period use or repetitive use.